On Tue 22-08-23 00:29:49, Mateusz Guzik wrote: > On 8/21/23, Mateusz Guzik <mjguzik@xxxxxxxxx> wrote: > > True Fix(tm) is a longer story. > > > > Maybe let's sort out this patchset first, whichever way. :) > > > > So I found the discussion around the original patch with a perf > regression report. > > https://lore.kernel.org/linux-mm/20230608111408.s2minsenlcjow7q3@quack3/ > > The reporter suggests dodging the problem by only allocating per-cpu > counters when the process is going multithreaded. Given that there is > still plenty of forever single-threaded procs out there I think that's > does sound like a great plan regardless of what happens with this > patchset. > > Almost all access is already done using dedicated routines, so this > should be an afternoon churn to sort out, unless I missed a > showstopper. (maybe there is no good place to stuff a flag/whatever > other indicator about the state of counters?) > > That said I'll look into it some time this or next week. Good, just let me know how it went, I also wanted to start looking into this to come up with some concrete patches :). What I had in mind was that we could use 'counters == NULL' as an indication that the counter is still in 'single counter mode'. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
